Update and Upgrade 404 errors

Hello there.

When I manually update and upgrade

Code:

sudo apt-get update && sudo apt-get upgrade

the following errors are mixed within the update/upgrade process

Code:

Err http://ppa.launchpad.net precise/main Sources
404 Not Found
Err http://ppa.launchpad.net precise/main i386 Packages
404 Not Found
W: Failed to fetch http://ppa.launchpad.net/chromium-daily/ppa/ubuntu/dists/precise/main/source/Sources 404 Not Found
W: Failed to fetch http://ppa.launchpad.net/chromium-daily/ppa/ubuntu/dists/precise/main/binary-i386/Packages 404 Not Found
E: Some index files failed to download. They have been ignored, or old ones used instead.

What does this mean, and how do I fix this?

Thanks

K.m

Edit: And also when there is software updates, it states that some could not be updated, such and such has to be installed. Then it says, it cannot be installed because ... and them two 404 up above appear.